Three of the men wore helmets and carried AK47s – a weapon once favoured by the IRA – with jackets reading ‘Gardai’ on the back.

Many witnesses said they mistook the men for genuine police before they began killing.

Two more men, one of whom was dressed as a woman, guarded the front door, while a sixth was the getaway driver.

A witness told The Irish Sun:

They were wearing masks and helmets. The weapons were massive, like the ones the IRA used to use.

It was initially reported that the attack was in retaliation for the death of Alan Ryan, a member of the Real IRA who was killed in September 2012 amid a feud with gang syndicates.

In the immediate aftermath, a supposed spokesperson for the Continuity IRA leadership warned more killings would follow. However, in a later statement a spokesman for the paramilitary group said they ‘did not have any involvement in Friday’s shooting’.

The BBC reporter Mark Devenport had written that Sinn Féin leader Gerry Adams had received death threats from the Continuity IRA, although Adams denied the IRA was still in existence in any shape or form.

Adams said:

It was a brazen attack in broad daylight by criminal thugs who believe they can operate with impunity and above the normal rule of law.

I understand a group calling itself the Continuity IRA has claimed responsibility for the attack at the Regency Hotel.

They are not the IRA. The IRA are gone and their weapons are gone.

Meanwhile, the another man has been shot dead in Dublin in what the Guardianreports is a retaliation for Bryne’s shooting.

. @GerryAdamsSF says Continuity IRA is not IRA "the IRA are gone and their weapons are gone" He says CIRA has him under active death threat

The latest victim of the gangland feud was shot at about 7.45pm on Monday evening, Irish police have said.

Irish police are now appealing for anyone who was in the area of the Regency Hotel between 2.00 and 2.45 pm, or anyone who was in the Charlemont Estate at that time to contact Ballymun Garda Station on 01 666 4400 or the Garda Confidential line 1800 666 111.’